The present invention relates to methods of producing an ink-jet recording head, and more particularly to a method of producing an ink-jet head using a thin-film deposition technology such as ion milling.
Conventionally, a wire-driving printer head has been widely used as a printer head. The wire-driving printer head performs printing by driving wires magnetically and pressing the wires against a platen with a paper sheet or an ink ribbon interposed therebetween. The wire-dot printer head, however, has many disadvantages such as large power consumption, noise generation, and low resolution, thus leaving much to be desired as a printer device.
Therefore, a printer employing an ink-jet recording head using piezoelectric elements or air bubbles generated by heat has been developed lately. The ink-jet recording head, which is driven noiselessly with low power consumption and achieves high resolution, has come to the front as a preferred printer device.
The ink-jet recording head basically includes nozzles, ink chambers, an ink supply system, an ink tank, and a pressure-generating part. In a printer using the ink-jet recording head, displacement generated in the pressure-generating part is transmitted to the ink chambers as pressure so that ink particles are sprayed from the nozzles, thereby recording characters or images on a recording medium such as a sheet of paper.
According to the conventional known method, a thin-plate piezoelectric element is attached to one side of the outer wall of an ink chamber as a pressure-generating part. By supplying a pulse-like voltage to the piezoelectric element, a composite plate formed of the piezoelectric element and the outer wall of the ink chamber deflects. Displacement generated by the deflection produces pressure that is applied to the ink chamber, so that ink is sprayed.
FIG. 1 is a schematic diagram showing an ink-jet recording head 10 and its periphery of a conventional printer 1, and FIG. 2 is a perspective view of the ink-jet recording head 10, showing the outline of a configuration thereof.
In FIG. 1, the ink-jet recording head 10 is attached to the-lower surface of a carriage 2. The ink-jet recording head 10 is positioned between a feed roller 3 and an eject roller 4 so as to oppose a platen 5. The carriage 2 includes an ink tank 6, and is provided to be movable in a direction perpendicular to the surface of the FIG. 1 sheet. A paper sheet 7 is pinched between a pinch roller 8 and the feed roller 3 and further between a pinch roller 9 and the eject roller 4 to be conveyed in the direction indicated by the arrow A. The ink-jet recording head 10 is driven and the carriage 2 is moved in the direction perpendicular to the sheet surface so that the ink-jet recording head 10 performs printing on the paper sheet 7. The printed paper sheet 7 is stored in a stacker 20.
As shown in FIG. 2, the ink-jet recording head 10 includes piezoelectric elements 11, individual electrodes 12 formed on the piezoelectric elements 11, a nozzle plate 14 having nozzles 13 formed therein, metal or resin ink chamber walls 17 forming, with the nozzle plate 14, ink chambers 15 corresponding to the nozzles 13, and a diaphragm 16.
The nozzles 13 and the diaphragm 16 are positioned to oppose the ink chambers 15. The periphery of the ink chambers 15 and the corresponding periphery of the diaphragm 16 are firmly connected, and the piezoelectric elements 11 cause the respective corresponding parts of the diaphragm 16 to be displaced as indicated by the broken line in FIG. 2. Voltages are applied to the piezoelectric elements 11 by supplying electrical signals from the main body of the printer to the individual piezoelectric elements 11 through a printed board not shown in the drawing. The piezoelectric elements 11 supplied with the voltages contract or expand to cause pressure in the respective ink chambers 15 so that ink is sprayed. Thereby, printing is performed on the recording medium.
The piezoelectric elements 11 are formed on the above-described conventional ink-jet recording head 10 shown in FIG. 2 by attaching plate-like piezoelectric elements to positions corresponding to the ink chambers 15 or by first attaching a piezoelectric element over the ink chambers 15 and then dividing the piezoelectric element according to the ink chambers 15.
If a thin piezoelectric element (smaller than 50 xcexcm) is employed in the thus produced conventional ink-jet recording head 10 in order to reduce the size thereof, a variation in the thickness of an adhesive agent used for the attachment causes variations in the displacement of the piezoelectric elements so that the characteristic of the ink head is deteriorated. Further, the piezoelectric element of this type has a problem in that a crack is made therein at the time of attachment.
Some inventors of the present invention, together with another inventor, have proposed a method of producing an ink-jet recording head using a thin-film deposition technology in order to eliminate the above-described disadvantage. However, there is still room for improvement in this method.
That is, a principal object of the present invention is to provide a method of producing a downsized ink-jet recording head of higher accuracy at low cost by making further improvements with respect to a method of producing an ink-jet recording head using a thin-film deposition technology.
The above object of the present invention is achieved by a method of producing an ink-jet recording head, the method including the steps of forming a piezoelectric layer subsequent to an electrode layer on a substrate by using a thin-film deposition technology, forming an energy-generating element for generating energy for ink ejection by etching the electrode layer and the piezoelectric layer simultaneously by ion milling, and removing a fence formed by deposits of mixed fine powders including those etched off the electrode layer and the piezoelectric layer by the ion milling.
In the present invention, an energy-generating element having integrality can be produced since the electrode layer and the piezoelectric layer are etched simultaneously by ion milling.
Further, a large area can be processed by etching by ion milling, and etching anisotropy is high. Accordingly, the shape of the energy-generating element can be designed freely, and its etched section is vertical without formation of unnecessary tapers.
Deposits of mixed fine powders generated by the ion milling are formed on the energy-generating element. However, by the step of removing the deposits, the periphery of the energy-generating element can be planarized before the subsequent production process is performed, so that an ink-jet recording head having a proper energy-generating element can be produced.
In the above-described step of removing the fence, the deposits of the mixed fine powders can be removed by using ion milling.
An ion milling angle herein is preferably greater than that in the step of forming the energy-generating element.
The ion milling angle in the step of removing the fence is smaller by five degrees than xcex8 obtained from the following equation, and the ion milling angle in the step of forming the energy-generating element preferably falls between 0 and 45xc2x0.
The ion milling angle for removing the fence differs depending on an element array space, a pattern resist thickness (wall height), and a pattern opening width, and an optimum ion milling angle is determined based on each dimension. For instance, a maximum angle in emission of argon (Ar) gas is determined by the following equation defined by the depth (from the surface of a resist pattern to a bottom formed after ion milling) and the width of an opening part:
xcex8=arctan (width/depth)
That is, the ion milling angle for removing the fence is set within the range of 0xc2x0 to xcex8 of the above-described equation, preferably between xcex8 (maximum) and xcex8-5xc2x0 approximately. In the ion milling for removing the fence, where etching is performed as in the ion milling for forming the pattern, the bottom part is etched to induce generation of a fence by contrast if the emission angle is set too upright (approximated to 0xc2x0).
CMP or wet etching can be employed in the step of removing the fence.